Recycling and treatment process for produced and used flowback fracturing water

ABSTRACT

A portable water recycling and treatment system and process for used and produced flowback frac water pumps the water from a collection tank through a series of dedicated hydration, retention and filtering tanks and vessels that provide treatment for the removal of chemicals, sediments and other containments. The system, which is enclosed, can be readily assembled on-site by interconnecting the dedicated tanks, vessels and pumps. The tanks and vessels may be situated in a plurality of trailers/units that are transported separately to the site.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/223,904, titled RECYLING AND TREATMENT PROCESSFOR PRODUCED AND USED FLOWBACK FRACTURING WATER, which was filed on Jul.8, 2009 by Chad Randal, the contents of which are incorporated herein inits entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to water recycling systems and, moreparticularly, to water recycling systems for use with water that isproduced and used in well fracturing or stimulation.

2. Background Information

Water used and produced in oil and gas well fracturing, or stimulation,operations requires treatment before re-use and disposal. The water istreated to remove chemicals that were added to the water before useand/or chemicals and sediment present in the water after use as aby-product of the well stimulation. The water, commonly referred to asused flowback fracturing (“frac”) water and produced water, may havebeen processed to ensure that it is capable of being used initially forstimulating oil and gas wells and is again processed for that purpose.In addition, the water is processed for disposal, e.g., to preventcontamination of ground water resources.

The water treatment facilities must be capable of treating the water forwide ranges of conditions including total dissolved solids, turbidity,different types and concentration of contaminants, off-gassing, and soforth. Thus, the water treatment facilities are generally complex andcostly to build and operate.

Typically, large quantities of the used flowback frac water and producedwater are pumped into trucks and transported from the well site to thewater treatment and/or disposal facilities and, for re-use, transportedback to the well site. Accordingly, traffic to and from the explorationareas is increased. When water re-use is not feasible because of, forexample, the economics of transporting the water back to the well siteafter treatment, the demands on local water resources can be enormousand may adversely affect the availability of ground waters for otherpurposes.

What is needed is a portable water recycling system and process that canbe established and run at or near a well site.

SUMMARY OF THE INVENTION

A portable water recycling and treatment system and process for used andproduced flowback frac water pumps the water from a collection tankthrough a series of dedicated hydration, retention and filtering tanksand vessels that provide treatment for the removal of chemicals,sediments and other containments. The system, which is enclosed, can bereadily assembled on-site by interconnecting the dedicated tanks,vessels and pumps. The tanks and vessels may be situated in a pluralityof trailers that are transported separately to the site. The operationsof the respective tanks and vessels are discussed in more detail below.

The system and process are to be used for the treatment of oilfieldwaste waters, flowback frac waters, oilfield produced waters, and anytype of water requiring pretreatment for use in fracturing service orfor preconditioning of waste waters to meet a potable waterspecification. However, the system and process are not limited to watertype, and may also be used for the treatment of high salinity watersthat require pretreatment and reduction of salinity via chemistryadditions and retention prior to treatment using membrane typetechnologies or other chemistries.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention description below refers to the accompanying drawings, ofwhich:

FIGS. 1 and 2 are overviews of the system and process;

FIG. 3 is a functional block diagram of a pumping sub-system andprocess;

FIG. 4 is a functional block diagram of a retention sub-system andprocess; and

FIG. 5 is a functional block diagram of a polishing sub-system andprocess.

DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT

A portable water recycling and treatment system and process aredescribed below for use in the oil and gas service industry, though thesystem and process are not limited to such use. In particular, in theillustrative embodiment, a system and process are described for treatingcontaminated flowback fracturing water used or produced at a well site.

Referring now to FIG. 1, a portable water recycling and treatment system100 includes an untreated water receipt tank 10, a treated water finishtank 12, and a waste tank 14, generally established at or near(proximate to) the well site. According to the illustrative embodimentsdescribed in more detail below, the system receives the contaminatedflowback fracturing water from the well site at the untreated waterreceipt tank, processes the water, and transports any residual materialsresulting from the treatment processes (such as, e.g., chemicals,contaminates, solids, flocculants, coagulants, gases, particulates, andmicrobes) to the waste tank. Treated water may then be supplied to thefinish tank for either re-use at the well site or further transportationaway from the site (e.g., for further processing or disposal).

The portable water recycling and treatment system 100 also includes anda plurality of portable and configurable containers, e.g., wheeled semitrailer units, 16 ₁, 16 ₂, and 16 ₃, referred to collectively byreference numeral 16, that contain dedicated tanks and vessels andassociated pumps as discussed below with reference to FIGS. 2-5,generally referred to as a pump subsystem and a treatment subsystem,depending on functionality (rather than physical orientation). Thetrailers may be transported to a location proximate to the well site,interconnected on-site with the tanks to complete the system, which is afully enclosed system that effectively handles fluid, solid, and gaswaste. The drawing depicts three trailers, one each for a pumpsubsystem, retention subsystem, and polish subsystem, however, thesystem may be constructed on fewer or more trailers, as appropriate, andrespective sub-system operations may be performed on single or multipletrailers. For ease of explanation, the three sub-systems are depicted inmore detail in FIGS. 3-5 and an overview of the system is depicted inFIG. 2.

Generally speaking, and as described in detail below, the pump subsystemand treatment subsystem are selectively configurable to pump and treatwater based on one or more characteristics of the contaminated water atthe particular site, one or more desired characteristics of treatedwater output from the containers, and a volume of water to be treated.The selective configuration may be accomplished through varying controlparameters, activating certain features, and making certaininterconnections (e.g., via the pump subsystem).

In other words, the interconnections basically consist of connecting thereceipt tank to the treatment subsystem, and the treatment subsystem tothe finish tank and waste tank, such that operation of the subsystems totreat the untreated water (treatment processes) pumps the untreatedwater of the receipt tank through the treatment subsystem, resulting intreated water entering the finish tank and residual materials enteringthe waste tank. At the same time, however, the pump subsystem andtreatment subsystem may be adjusted at the well site to accommodatevarious conditions, or may be initially configured (e.g., prior totransport to the site) to account for expected conditions. For example,as described herein, various treatment processes (and interconnections)may be selectively adjusted (and/or omitted) based the input water oroutput water characteristics, how much water is to be treated, at whatrate, at what temperature, etc.

Referring now to FIGS. 1-5, the system 100 takes contaminated flowbackfracturing water collected in the receipt tank 10, which in the exampleis a 400 bbl collection tank, and pumps the water for treatment througha pump sub-system operating on the pump trailer 16 ₂ to a hydration tank300 or 301 on the pump trailer 16 ₂ or retention trailer 16 ₃. As thewater is pumped between the collection tank and the hydration tank,chemical add from one or more chemical tanks 202 may be supplied viachemical pumps 210 to chemically treat the water (at vessel 20). Thechemical add and water may be mixed in the hydration tank by a paddletype assembly (not shown) or with in line mixers. In addition, a vacuumchamber 512 may be added into the system and process, to strip anyentrained light hydrocarbons, N₂ or CO₂ or methanol and H₂S out of thewater at conditions of up to and over 4.3 psia vacuum and temperaturesup to 70 Celsius. The released gases that are vacuumed may be sent tothe waste tank or other storage or treatment facility, or, whereappropriate, released into the atmosphere.

The water next passes from the hydration tank 300 through a hopper 301for further mixing and hydration of an H₂S (hydrogen sulfide) scavenger,oxidizers, coagulants, or flocculants in the water, to one or morelarger tiered retention vessels 302 on the retention trailer 16 ₁. Theretention vessels allow the settling of the chemical add, which mayconsist of various flocculants and coagulants and other chemicals usedto scavenge out H₂S and residual pumping industry chemistry, as well asother classified contaminants targeted for removal. The water is flowedthrough the sludge concentration in the bottom of the retention vesselsor showered down on top of the settling water, depending on flocculantused, to remove contaminants including solids and total dissolved solids(“TDS”), as appropriate. The residual contaminants (e.g., settledchemicals or contaminates) are periodically siphoned off from theretention vessels 302 to the waste tank 14 by the pumping sub-system,and gases are vented to the waste tank and/or an H₂S scrubber attachedto tank 14 in FIG. 1. The water may then be decanted from the retentionvessels through a dump tank 304, that also provides to the waste tank 14any residual waste that can be skimmed from the water and transported tothe waste tank.

Notably, at whichever configured stage where chemicals may be added tothe water, a type, an amount, or a mixture of chemicals to be added maybe adjusted (e.g., dynamically by a control subsystem) based on variousfactors. Such factors may comprise the characteristics of thecontaminated water, the desired characteristics of treated water output,the volume of water to be treated, and a temperature of the water (e.g.,adding methanol to keep the water from freezing in the winter or coldclimates). For example, certain chemicals may be added to the water totreat the water as may be understood by those skilled in the art, suchas oxidizers, coagulants, flocculants, H₂S scavenging chemicals,methanol, and various mixtures of chemicals as appropriate.

Referring now also to FIG. 5, the water is pumped from the dump tank 304through a clarifier 500 that is packed with multimedia material 502 thatis laid inside the vessel or tank at angles designed to optimize surfacecontact for water and prevent contaminant build up in the media that mayplug the clarifier. Essentially, clarified water passes to the surface,gas breaks out (is released) and is vented to the waste tank 14, andsolids and carry over flocculant drop out to the bottom of the vesselfor further removal to the waste tank as sludge. The clarified water isthen provided to a drop/catch tank 506 that builds retention volume.

Next, the water is pumped through a series of back wash capablemultimedia filters 508 that are packed with media (e.g., apolyelectrolyte) that attracts additional particles that may have beencarried over from the clarification process. The waste from the filterprocess is supplied to the waste tank 14, while the filtered water nextpasses through a series of staged filtration vessels 510 that havefiltration capability to filter the water down to 1 micron absolute. Thestaged filtration vessels operate as a high pressure filter bag assemblythat is illustratively sized at over 10 times the required processingrates, and can operate over a range from 50 microns to 1 micronabsolute, as appropriate, to condition the water for re-use or disposal.As shown, the filtration vessels provide 10, 5 and 1 micron polishes,though other polishes may be utilized in addition or in the alternative.The process rates in the example run up to 60 m³/hr. Further, a vessel514 for light purification (e.g., germicidal UV light or otherwise) maybe included, to kill microbes that may be present in the water. Thetreated water, which is suitable for either re-use or disposal, is thensupplied to a finish tank 16.

When filtering particulates from the water, one or more filteringproperties (e.g., media, polish levels, etc.) may be adjusted based onthe characteristics of the contaminated water and the desiredcharacteristics of treated water output. For instance, suchcharacteristics may correspond to contaminate particle sizes in thecontaminated water, total dissolved solid (TDS) size in the contaminatedwater, contaminate particle sizes in the treated water, and TDS size inthe treated water.

The timing of the various process steps, such as mixing and hydrationprocesses, are controlled through a control panel 206 (e.g., controlsubsystem), and specific reaction times associated with various chemicaladds can be readily accommodated. Accordingly, the chemical adds can bevaried based on the condition of the water (e.g., types of contaminates)at the start and the use to which the water is to be directed aftertreatment. In other words, a variable time that a volume of waterremains in a particular component (vessel) may be adjusted based on thecharacteristics of the contaminated water and the desiredcharacteristics of treated water output, and/or based on solids or gasesto be removed from the contaminated water. As shown in FIG. 3,additional or alternative chemicals may be stored in work tanks 208 andpumped into the chemical work tanks 202, by pumps 210, for use in watertreatment as needed.

The system and process 100 described above are highly flexible and canbe used to treat water of varying qualities, from high to low TDS,and/or various levels of hydrocarbon and water chemistry contaminants,and so forth. The onsite configuration of equipment also allows variablevolumes of water to be treated on an economic commercial scale. Thesystem and process can be run at temporary or permanent centralizedlocations or on a well site, where the produced and back flow frac wateris flowing back to the surface.

Additionally, the pump subsystem and treatment subsystem may be adjustedbased on whether the treated finish tank water is reused at the site ortransported away from the well site (e.g., disposed to a location awayfrom the site). For example, whether the water is to be reused for welloperations, disposed of, or further treated away from the site, thesystem 100 may be configured to produce appropriate water at the finishtank.

Advantageously, the portable water recycling and treatment system andprocess described herein may be used to efficiently treat contaminatedflowback fracturing water used or produced at a well site (or othersuitable water treatment locations). In particular, by allowing the pumpsubsystem and treatment subsystem to be selectively configurable basedon characteristics of the contaminated water input and/or output at theparticular site, a portable water recycling system and process that canbe established and run at or near a well site is effectively provided.

For instance, as noted above, the portable system has variable waterchemistry treatment add capability and allows for variable mix andhydration times of the chemicals, to satisfy specific reaction times.The system further has a retention capability for varied chemicalreactions and treatment of particulates, fines or solids measured inincrements of NT or turbidity from 0-1000 ppm.

The system and process are also capable of utilizing concentrationtechniques and reactions of effective sludge beds that are used as partof the treatment process, via by-products and from chemical treatmentsuch as varied amounts and/or types of water flocculants. The system isessentially an enclosed system, and has the capability to handlepotential off gas associated with the water, such as CO₂, N2, H₂S andC1-C7 light carbon chains in varying concentrations.

Moreover, the clarification process allows high surface area filtrationwith inclined fixed media and long contact time, and the follow-onpolishing steps have reduced backwash frequency through the multimediafilters. The filtration capability is able to handle high levels of ironremoval, by various methods of multimedia filtration that allow thewater to then be gelled and crosslinked once the iron and othercontaminants are removed.

Further, the system and process thus provide a consistent water qualitythat is suitable for reuse of the water for well stimulation or fordisposal. The system and process further reduces the solids and TDScontent and fines picked up during the flowback process to levels thatallow economic filtration and purification processes to be used posttreatment.

The foregoing description has been directed to specific embodiments. Itwill be apparent, however, that other variations and modifications maybe made to the described embodiments, with the attainment of some or allof their advantages. For instance, it is expressly contemplated that thecomponents and/or elements described herein can be used for watertreatment other than flowback fractured well site water. Also, while aparticular order of particular treatment processes have been shown anddescribed, those skilled in the art will appreciate that other processorders, arrangements, orientations, etc., may be used to treat water,and that the system described herein is merely an illustrativeembodiment. Accordingly this description is to be taken only by way ofexample and not to otherwise limit the scope of the embodiments herein.Therefore, it is the object of the appended claims to cover all suchvariations and modifications as come within the true spirit and scope ofthe embodiments herein.

What is claimed is:
 1. A method for use with treating contaminatedflowback fracturing water used or produced at a well site, the methodcomprising: establishing, proximate to the well site, a treated waterfinish tank, a waste tank, and an untreated water receipt tank toreceive the contaminated flowback fracturing water from the well site;transporting one or more portable and configurable containers proximateto the well site, the containers comprising at least a pump subsystemand a treatment subsystem, the pump subsystem and treatment subsystembeing selectively configurable to pump and treat water based on one ormore characteristics of the contaminated water at the particular site,one or more desired characteristics of treated water output from thecontainers, and a volume of water to be treated; interconnecting, viathe pump subsystem, the receipt tank to the treatment subsystem, and thetreatment subsystem to the finish tank and waste tank; and operating thesubsystems to treat the untreated water, wherein the untreated water ofthe receipt tank is pumped by the pump subsystem through the treatmentsubsystem, resulting in treated water entering the finish tank andresidual materials entering the waste tank.
 2. The method as in claim 1,wherein the subsystems comprise one or more components, the methodfurther comprising: adjusting a variable time a volume of water remainsin a particular component based on the characteristics of thecontaminated water and the desired characteristics of treated wateroutput.
 3. The method as in claim 2, wherein the variable time isadjusted based on at least one of either solids or gases to be removedfrom the contaminated water.
 4. The method as in claim 1, furthercomprising: adding chemicals to the water to treat the water; andadjusting at least one of either a type, an amount, or a mixture ofchemicals to be added based on at least one of either thecharacteristics of the contaminated water, the desired characteristicsof treated water output, the volume of water to be treated, and atemperature of the water.
 5. The method as in claim 4, wherein thechemicals added are selected from a group consisting of: oxidizers,coagulants, flocculants, H₂S scavenging chemicals, methanol, and amixture of chemicals of the group.
 6. The method as in claim 1, furthercomprising: filtering particulates from the water with one or morefilters; and adjusting a filtering property of one or more of thefilters based on the characteristics of the contaminated water and thedesired characteristics of treated water output.
 7. The method as inclaim 6, wherein the characteristics of the contaminated water and thedesired characteristics of treated water output upon which the filteringproperty is based correspond to at least one of either contaminateparticle sizes in the contaminated water, total dissolved solid (TDS)size in the contaminated water, contaminate particle sizes in thetreated water, and TDS size in the treated water.
 8. The method as inclaim 1, further comprising: adjusting the pump subsystem and treatmentsubsystem based on one or more types of contaminates in the contaminatedwater.
 9. The method as in claim 1, further comprising: adjusting thepump subsystem and treatment subsystem based on whether the treatedfinish tank water is reused at the site or transported away from thesite.
 10. The method as in claim 9, further comprising: adjusting thepump subsystem and treatment subsystem for when the treated finish tankwater is transported away from the site based on a further treatment tobe applied to the treated finish tank water away from the site.
 11. Themethod as in claim 1, further comprising: siphoning, by the treatmentsubsystem, H₂S from the water during operation.
 12. The method as inclaim 1, further comprising: adjusting the pump subsystem and treatmentsubsystem while the one or more containers are located proximate to thewell site.
 13. A system for use at a well site having a contaminatedflowback fracturing water supply, the system comprising: an untreatedwater receipt tank configured to receive the contaminated flowbackfracturing water from the well site; a treated water finish tank; awaste tank; one or more portable and configurable containers proximateto the well site, the containers comprising at least a pump subsystemand a treatment subsystem, the pump subsystem and treatment subsystembeing selectively configurable to pump and treat water based on one ormore characteristics of the contaminated water at the particular site,one or more desired characteristics of treated water output from thecontainers, and a volume of water to be treated; one or moreinterconnections configured to interconnect, via the pump subsystem, thereceipt tank to the treatment subsystem, and the treatment subsystem tothe finish tank and waste tank; and a control subsystem configured tooperate the pump subsystem and treatment subsystem to treat theuntreated water, wherein the untreated water of the receipt tank ispumped by the pump subsystem through the treatment subsystem, resultingin treated water entering the finish tank and residual materialsentering the waste tank.
 14. The system as in claim 13, wherein at leastone of the pump subsystem and treatment subsystem further comprise oneor more components, the control subsystem further configured to adjust avariable time a volume of water remains in a particular component basedon the characteristics of the contaminated water and the desiredcharacteristics of treated water output.
 15. The system as in claim 14,wherein the variable time is adjusted based on at least one of eithersolids or gases to be removed from the contaminated water.
 16. Thesystem as in claim 13, further comprising: at least one chemical adderconfigured to add chemicals to the water to treat the water, wherein atleast one of either a type, an amount, or a mixture of chemicals to beadded is adjustable based on at least one of either the characteristicsof the contaminated water, the desired characteristics of treated wateroutput, the volume of water to be treated, and a temperature of thewater.
 17. The system as in claim 16, wherein the chemicals added areselected from a group consisting of: oxidizers, coagulants, flocculants,H₂S scavenging chemicals, methanol, and a mixture of chemicals of thegroup.
 18. The system as in claim 13, further comprising: one or morefilters configured to filter particulates from the water, wherein afiltering property of one or more of the filters is adjustable based onthe characteristics of the contaminated water and the desiredcharacteristics of treated water output.
 19. The system as in claim 18,wherein the characteristics of the contaminated water and the desiredcharacteristics of treated water output upon which the filteringproperty is based correspond to at least one of either contaminateparticle sizes in the contaminated water, total dissolved solid (TDS)size in the contaminated water, contaminate particle sizes in thetreated water, and TDS size in the treated water.
 20. The system as inclaim 13, wherein the control subsystem is further configured to adjustat least one of either the pump subsystem or the treatment subsystembased on one or more types of contaminates in the contaminated water.21. The system as in claim 13, further comprising: wherein the controlsubsystem is further configured to adjust at least one of either thepump subsystem or the treatment subsystem based on whether the treatedfinish tank water is reused at the site or transported away from thesite.
 22. The system as in claim 21, further comprising: wherein thecontrol subsystem is further configured to adjust at least one of eitherthe pump subsystem or the treatment subsystem for when the treatedfinish tank water is transported away from the site based on a furthertreatment to be applied to the treated finish tank water away from thesite.
 23. The system as in claim 13, wherein the system is fullyenclosed.
 24. The system as in claim 13, wherein the containers arewheeled semi trailers.
 25. A method for treating contaminated flowbackfracturing water used or produced at a well site, the method comprising:collecting contaminated flowback fracturing water in a receipt tankproximate to the well site; pumping, via a pump subsystem at the sitelocated within a portable and configurable container proximate to thewell site, the contaminated water through a treatment subsystem that isproximate to the well site and located within a portable andconfigurable container; treating the contaminated water, by thetreatment subsystem, through treatment processes comprising: i) addingone or more chemicals to the water to chemically treat the water; ii)allowing the water and any chemicals and contaminates to settle and anygases in the water to release; iii) siphoning any settled chemicals orsettled contaminates; iv) clarifying the water through a clarifierpacked with multimedia material to remove any solids, remove anyflocculants, and release gases in the water; vi) filtering the waterthrough one or more filters to remove particulates from the water; andvii) purifying the water through microbial purification; selectivelyadjusting at least one of the treatment processes based on one or morecharacteristics of the contaminated water at the particular site, one ormore desired characteristics of treated water output from thecontainers, and a volume of water to be treated; transporting anyresidual materials resulting from the treatment processes to a wastetank located proximate to the well site, the residual materials selectedfrom a group consisting of: chemicals, contaminates, solids,flocculants, coagulants, gases, particulates, and microbes; andsupplying the treated water to a finish tank located proximate to thewell site.
 26. The method as in claim 25, wherein selective adjustingfurther comprises: omitting a particular treatment process.
 27. Themethod as in claim 25, wherein the treatment processes further comprise:viii) decanting the water; and ix) skimming residual materials from thedecanted water, the skimmed residual material being transported to thewaste tank.
 28. The method as in claim 25, further comprising: vacuumingthe released gases to the waste tank.
 29. The method as in claim 25,further comprising one of either: reusing the treated water at the wellsite; or disposing the treated water to a location away from the wellsite.